Lit candles can be a fire hazard. Just ask fictional teacher Barbara Howard, of ABC’s Abbott Elementary, or pop stars Taylor Swift and Gracie Abrams. Between 2018 and 2022, candles started 4% of home fires, according to the National Fire Prevention Association, and 21% of those fires started from an “unattended, discarded, or otherwise misused” candle.
One way to reduce fire risk is to trim the wick to ¼ inch after the wax has cooled, which helps to keep the flame smaller. And never leave a lit candle unattended, especially around children or pets.
While a candle warmer eliminates the dangers of an open flame, there are still some safety risks. When the warmer is in use (and for about 15 minutes afterward), it’s hot to the touch. As with a lit candle, with a warmer you should be careful where you place it, and be mindful of the materials that are close to the device. You’ll also want to make sure the outlet or extension cord is safe to use.
In the third hour of burn testing, I detected a hint of a burning smell from the warmer. I was worried, but out of curiosity, I did not interrupt the test (though, prepared for a worst-case scenario, I had a fire extinguisher within reach). Eventually, the scent became less noticeable and ultimately went away, but it did make me nervous about using the warmer again.
There’s also the question of indoor air pollution. Indoor air pollution is a multifaceted, complex topic, but scented products and smoke are common contributors. With regard to candles, there are a few things to be mindful of: volatile organic compounds (VOCs) and particulate matter.
In a scented candle, the gaseous VOCs actually provide the product’s main draw: the scent. And the VOCs do contribute to indoor air pollution, but particulates are introduced when the candle is lit.
“Fine particles are pretty much invisible to the human eye and can be formed by all kinds of things,” said Katherine Pruitt, national senior director of policy at the American Lung Association, noting that combustion is a common producer of particulate matter. Particulates can affect your heart and your lungs, and they can even get into your bloodstream.
Natalie Johnson, chair of the interdisciplinary program of toxicology at the Texas A&M School of Public Health, pointed out that “anytime you have something burning, you’re going to have a mixture of both” gases and particles.
Burning a candle wick is no exception. Gases are released from the candle, and soot is a particulate.
Using a candle warmer eliminates the introduction of soot, but it does not eliminate the gaseous component, which can still introduce health risks.
“Personally, I am an advocate for using the candle warmers because you are going to prevent the combustion and decrease the particle pollution,” Johnson said.
The number one thing Johnson and Pruitt advised was to use scented candles less frequently, which you might not want to do (I know I don’t). If that’s the case, they also recommended taking steps to improve your indoor air quality, like opening a window and using an air purifier. (If you want to read about other steps you can take, check out this piece by Wirecutter’s sustainability editor, Katie Okamoto.)
But there is one important safety note to consider: If you’ve already used a candle with a warmer, you shouldn’t switch to lighting the wick because it may have shifted out of its central position. An expert from the NCA told us that if a lit wick is too close to the side of a glass container, it may create a hot spot and the glass container could shatter. Switching the other way—from lighting to warming—should be fine, but the wick may become buried in wax in the process.
The verdict: half a point for candle warmers
